2-Carboxyethyl)phenyl)phosphinic acid, a flame retardant additive for polymers such as polyesters, has been prepared by first reacting of acrylic acid with dichloro(phenyl)phosphine. However, the reactants have been used in molar equivalent proportions, after which the addition product, 3-(chlorophenylphosphinyl) propionyl chloride, was isolated by a difficult distillation. This addition product was then subjected to a separate hydrolysis step to obtain the 2-carboxyethyl(phenyl)phosphinic acid in yield insufficient for commercialization, A. N. Padovik et al, "Reaction of Phenylphosphous dichloride with Acrylic Acid," Zhural Obshohei Khimii, 37, No. 2, pages 423-427 (1967).